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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef UI_BASE_EVENTS_EVENT_DISPATCHER_H_
#define UI_BASE_EVENTS_EVENT_DISPATCHER_H_
#include "base/auto_reset.h"
#include "ui/base/events/event.h"
#include "ui/base/events/event_constants.h"
#include "ui/base/events/event_target.h"
#include "ui/base/ui_export.h"
namespace ui {
class EventDispatcher;
class UI_EXPORT EventDispatcherDelegate {
public:
EventDispatcherDelegate();
virtual ~EventDispatcherDelegate();
// Returns whether an event can still be dispatched to a target. (e.g. during
// event dispatch, one of the handlers may have destroyed the target, in which
// case the event can no longer be dispatched to the target).
virtual bool CanDispatchToTarget(EventTarget* target) = 0;
// Returns the event being dispatched (or NULL if no event is being
// dispatched).
Event* current_event();
protected:
// Dispatches the event to the target. Returns true if the delegate is still
// alive after dispatching event, and false if the delegate was destroyed
// during the event dispatch.
bool DispatchEvent(EventTarget* target, Event* event);
private:
EventDispatcher* dispatcher_;
DISALLOW_COPY_AND_ASSIGN(EventDispatcherDelegate);
};
// Dispatches events to appropriate targets.
class UI_EXPORT EventDispatcher {
public:
explicit EventDispatcher(EventDispatcherDelegate* delegate);
virtual ~EventDispatcher();
void ProcessEvent(EventTarget* target, Event* event);
const Event* current_event() const { return current_event_; }
Event* current_event() { return current_event_; }
bool delegate_destroyed() const { return !delegate_; }
void OnHandlerDestroyed(EventHandler* handler);
void OnDispatcherDelegateDestroyed();
private:
void DispatchEventToEventHandlers(EventHandlerList& list,
Event* event);
// Dispatches an event, and makes sure it sets ER_CONSUMED on the
// event-handling result if the dispatcher itself has been destroyed during
// dispatching the event to the event handler.
void DispatchEvent(EventHandler* handler, Event* event);
EventDispatcherDelegate* delegate_;
Event* current_event_;
EventHandlerList handler_list_;
DISALLOW_COPY_AND_ASSIGN(EventDispatcher);
};
} // namespace ui
#endif // UI_BASE_EVENTS_EVENT_DISPATCHER_H_
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